1. Field of the Invention
This invention relates to the filtering of a fluid and more particularly to an improved seal for sealing a filter element to a filter mounting and the method of making the seal. This invention also relates to an improved frangible seal for sealing a filter element to a filter mounting and the method of making the frangible seal.
2. Background of the Invention
Various apparatuses and methods have been utilized by the prior art for removing suspended contaminants from a contaminated fluid. In general, the contaminated fluid is passed through a porous filtering media by an external pressure or an external force. The pore size of the porous filtering media is selected to permit the passage of the fluid therethrough while inhibiting the flow of contaminants through the porous filtering media. The contaminants are blocked by the porous filter media while the fluid passes through the porous filter media. The fluid flowing through the filter media is purged of the contaminants.
After a period of time, the contaminants collected by the filter media overlay the pores of the porous filter media thereby blocking the pores and reducing the passage of the fluid therethrough. The blockage of the pores of the filter media by the collected contaminants reduce the flow rate of the fluid through the fluid filter thereby rendering the fluid filter unsuitable for continued used. In many cases, the fluid filter was discarded and replaced with a new fluid filter to reestablish the desired flow rate of the fluid in the fluid filtering process.
In a typical fluid filter, a porous filter media is secured to a filter support or the like for mounting or suspending the filter media. In the case of a cylindrical filter, the filter media is formed into a cylindrical configuration and a first and a second cylindrical end of the filter media is bonded to a first and a second filter mounting member such as a first and a second end cap. The first and second end caps mount the filter media relative to a fluid input source and a fluid output source.
In many cases, a welding process was used for affixing the first and second cylindrical ends of the filter media to the first and second end caps. The welding process was accomplished by first placing the filter media on a supporting core. The first and second cylindrical ends of the filter media were swaged to compact the filter media onto an underlying supporting core. A first and a second welding ring were welded to the compacted first and second ends of the filter media. Finally, the first and second end caps were welded to the first and second welding rings. The compacting and welding of the first and second cylindrical ends of the filter media essentially destroyed all filtering capability of the filter media near the compacted ends of the filter media.
Others in the prior art have devised devices and methods for creating a bond between the filter media and the filter support. These other devices and methods have used means other than welding to affix a filter media and the filter support.
U.S. Pat. No. 2,642,187 to Bell discloses a replaceable filter unit of the character described comprising a pleated filter body of resin-impregnated paper arranged in tubular form and with the pleats extending substantially radially, end discs of the same material as the filter body closing off opposite ends of the body, said discs being bonded by a thermosetting resin adhesive to opposite end edges of said pleats, said adhesive lying between under faces of said discs and corresponding end edges of said pleats in contact therewith, and having turned down rims bonded adhesively by thermosetting resin adhesive to folds of the pleats, said adhesive lying between inner faces of the turned down rims and the folds of the pleats in contact therewith.
U.S. Pat. No. 2,877,903 to Veres discloses a unit for filtering particulate matter from a fluid flowing therethrough, a hollow filter body comprising a screen equipped with a screen closure at one end thereof, a cap substantially closing the other end of said screen body and defining connecting means for communicating the interior of said filter body with a fluid flow line, and a mass of pellets defining a substantially continuous coating along the outer surface of the screen end closure and screen body and being bonded to each other and to the screen body and end closure to form an integrated structure therewith, whereby both said screen body and screen end closure define filtering areas through which fluid may pass to the interior of the screen body.
U.S. Pat. No. 2,957,235 to Steinberg discloses a method of assembling first and second elements composed of a mixture of powdered metal and resinous binder comprising placing said first element on a support, heating said first element until said resin binder therein becomes pliable without the element losing shape, placing said second element against said first element, applying pressure to said second element until a bond is formed by the resinous binder between said first and second elements, removing the elements from said support, cooling the assembly of said elements, supporting said assembly with sinter material in a sintering zone, and sintering said assembly into a unitary sintered structure.
U.S. Pat. No. 3,379,000 to Webber et al discloses a tow of metal filaments each having a maximum cross-section of less than approximately 10 microns and a length of approximately 50 feet and having a trace amount of a different material diffused in the outer surface thereof.
U.S. Pat. No. 3,490,902 to Fisher discloses a method for forming porous structures useful, for example, as filters, diffusion membranes, sound absorbers, and the like. The structures contain a sintered metal portion at least one surface of which having embedded and bonded thereto a reinforcing member. Some of the fibers in the fiber metal portion are bonded to each other and to the reinforcing member.
U.S. Pat. No. 3,505,038 to Luksch et al. discloses a mass comprising a plurality of randomly disposed hair-like substantially solid metal fibers, wherein said fibers are substantially free from particles of degradation and air transportable, and wherein said mass has resilient loft, substantial uniformity of density and distribution of voids, handlable green strength, and a density range of from one percent to eighty-five percent.
U.S. Pat. No. 3,716,347 to Bergstrom et al. discloses metal parts joined together with sintered powdered metal by applying a mixture of powdered metal and an organic heat-fugitive binder to the parts at the locus of the joint to be formed therebetween, assembling the parts in their desired joined configuration, and heating the assembly to volatilize or burn-off the binder and sinter the powdered metal.
U.S. Pat. No. 4,114,794 to Storms discloses an autogenous or sinter bond between metallic filter media and other metal components of a filter assembly is produced by joining the parts through a diffusion bonding membrane. The membrane comprises a web of small diameter metal fibrils which will sinter bond to both the filter media and the other filter parts to form a physically strong and leak-free seal.
U.S. Pat. No. 4,169,059 to Storms discloses an autogenous or sinter bond between metallic filter media and other metal components of a filter assembly is produced by joining the parts through a diffusion bonding membrane. The membrane comprises a web of small diameter metal fibrils which will sinter bond to both the filter media and the other filter parts to form a physically strong and leak-free seal.
U.S. Pat. No. 4,290,889 to Erickson discloses a new and unique means for preventing the crowns of a backflushable filter element unit from splitting which has heretofore been caused by the cyclic action of the cleaning and backflushing. A layer of staple material is positioned adjacent the outer layer of filter media to prevent bellowing or ballooning. An additional staple layer may be positioned adjacent the inner layer of filtered media to provide additional support. With both staple layers in position on both sides of the filter media, the media is firmly captured and the crowns will not split.
U.S. Pat. No. 4,676,843 to Nazmy discloses two component workpieces consisting of different superalloys or of the same superalloy are bonded together to form a monolithic whole, with the insertion of a layer consisting of a powder of composition similar to or identical to that of the component workpieces by hot pressing in accordance with the diffusion bonding process. The workpiece surfaces to be bonded do not have to have narrow tolerances, but are with advantage provided with grooves. The process is suitable for the bonding together of component workpieces consisting of a dispersion-hardened, nickel-based superalloy or of component workpieces of such an alloy and workpieces consisting of a cast conventional superalloy.
U.S. Pat. No. 4,875,616 to Nixdorf discloses a method for producing a high temperature, high strength bond between a ceramic shape and a metal substrate, such as joining a ceramic cap to a piston for an internal combustion engine. The composite joint is effected through the use of a ceramic perform fabricated using fibers, whiskers, platelets or sponge-like particles having the same composition as the ceramic body. The preform is joined to the ceramic shape by using a ceramic slip having a ceramic corresponding in composition with the ceramic body, with this juncture being heated to achieve a secure bond. The preform is joined to the metal substrate by first infiltrating the preform with molten material corresponding to the substrate, and then pressure bonding the infiltrated preform to the substrate after the molten material has solidified. The substrate can be metal or metal alloy. An example is given for the bonding of silicon carbide to a 300 series aluminum.
U.S. Pat. No. 5,230,760 to Tanabe discloses a filter cartridge of micro filtration membrane pleats type, by which it is possible to stably manufacture products of high quality and to reduce the manufacturing cost. In the method for manufacturing a filter cartridge of micro membrane pleats according to the present invention, an initial portion and a last portion with pleats of a micro filtration membrane are welded together to prepare an endless micro membrane, and a filter element provided with a micro filtration membrane is welded on two end plates. A thin bonding auxiliary plate made of the same material as the end plates, having an opening at its center and molten at relatively low temperature, is welded to filter element and end plates which are heated in advance.
U.S. Pat. No. 5,279,733 to Heymans discloses filter candle apparatus comprising an elongated mesh pack defining an axial opening therethrough and having an end cap fixedly secured to one end and an end fitting fixedly secured to the opposite end. The end fitting defines an opening therethrough which is coaxial with the axial opening of the mesh pack. A hollow core tube defines a plurality of openings therein positioned within the axial opening of the mesh pack and being removably slidable therethrough. The core tube has an end member surrounding one end thereof that engage the end fitting of the mesh pack. A ring-shaped bearing is recessedly held within and by the end fitting of the mesh pack and engaging the core tube proximate the end member. An outer guard defines apertures therein adjacently surrounding the mesh pack.
U.S. Pat. No. 5,350,515 to Stark et. al. discloses a filter cartridge including a cylindrical filter medium potted into a top cap, and having an internally potted bottom closure molded in place inside the filter medium.
U.S. Pat. No. 5,395,039 to Koehler et. al. discloses such a braze material and process. The same braze material and process is disclosed by a prior NICROBRAZ Technical Bulletin of 1991 published by the Wall Colmony Corporation regarding a braze material sold under the trademark xe2x80x9cNICROBRAZxe2x80x9d.
U.S. Pat. No. 5,545,323 to Koehler et al. discloses a filter assembly and a method of making a filter assembly described wherein a filter pack is seated in an end cap and contacted with a particulate material and a settling liquid of low viscosity to form a filter assemblage. The filter assemblage is sintered to form a strong, virtually impermeable bond therebetween.
Others in the prior art have devised devices and methods for cleaning the fluid filter to remove the contaminants collected by the filter media. Typically, the process of removing the contaminants from the filter media involved the flow of a solvent material such as acids, bases and organics or the like through the filter media in a direction opposite to the direction of the fluid through the fluid filter. In some cases, the solvent material was passed through the filter media when the fluid filter was raised to an elevated temperature.
The filter media that is capable of being cleaned by a flowing solvent at an elevated temperature must be constructed in an entirely different manner and using entirely different materials in order to withstand the process of cleaning the filter media. The filter media that is capable of being cleaned must be capable of withstanding the reverse flow of a solvent as well as must be capable of withstanding the elevated temperature.
The filter media that is capable of withstanding the reverse flow of a solvent and/or an elevated temperature is more costly than the filter media of a disposable filter. Likewise, the material used to secure the filter media within the fluid filter must be capable of withstanding the solvent and the elevated temperature. The increased cost of the materials of the reusable fluid filter added substantially to the overall manufacture cost of the reusable fluid filter. Accordingly, reusable fluid filters have not found widespread use in many applications since the cost of such filters prohibits the widespread use thereof.
U.S. Pat. No. 945,632 to Strahl discloses a filter comprising a casing, a perforated tube therein, spaced caps removably mounted upon the tube, and filter material between the tube and the casing. The caps have members extending longitudinally of the tube over the material to hold the same in place.
U.S. Pat. No. 2,413,991 to Newman discloses in a filter, the combination of a substantially cylindrical central cone member of apertured sheet metal, the core member being provided upon its upper end with an annular metal fitting of tubular shape threaded to be engaged by a tubular threaded member. A substantially flat annular metal member has an inwardly extending cup-shaped cylindrical formation received in and secured to the core and having a radially extending flange for supporting a gasket. The radially extending flange also carries an inwardly turned cylindrical retaining flange. A similar metal member for the opposite end of the filter, comprises an annular member having an inwardly extending cup-shaped depression, a flat annular flange for receiving a gasket and an inwardly extending cylindrical retaining flange. The latter cup-shaped member has an aperture to receive the threaded tubular portion of the fitting. A filter unit of stiff characteristics is adapted to resist compression as a column, the filter unit being interposed between the gaskets of the first cup-shaped member and the second cup-shaped member and clamped between the gaskets by means of the tubular threaded member.
U.S. Pat. No. 3,423,909 to Bennett et al. teaches an air cleaner of the dry type having a housing, an air inlet, a wall member, a clean air outlet through the wall member and an opening for dust removal. A filter element assembly includes a generally cylindrical outer screen mounted in the housing to separate coarser matter from finer matter and a porous filter element concentrically disposed within the outer screen through which the incoming air is passed to separate out matter in suspension. An inner screen is concentrically disposed within the porous filter element. The inner screen is wire mesh to separate out additional matter passing through the assembly. A first and second sealing means are located respective the first and second ends of the filter element. The ends of the inner and outer screens are molded into the sealing means for providing a seal for the filter element assembly. The filter element assembly is disposed within the housing coaxially with the clean air outlet, the first sealing means engaging the wall member around the clean air outlet.
U.S. Pat. No. 3,498,464 to Frosolone discloses a filter cartridge for filtering out particulate matter in used solvents such as perchloroethylene used in dry cleaning systems. The filter cartridge is of a knockdown construction for ready replacement and reuse having interfitted perforated tubes.
U.S. Pat. No. 4,186,099 to Henschel, Jr. et al. sets forth a consumer rebuildable filter cartridge for mounting in a fluid filter chamber in a fluid flow path which includes inner and outer perforated tubular members mounted coaxially on a fixed end cap to form an annular chamber. A filter element of pleated sheet filter material is formed in a tubular construction and fitted into the annular space defined between the inner and outer tubular members and is sealed at each end by suitable resilient seal washers, compressed between the fixed end cap and a movable end cap. The inner and outer tubular members forms support structure for supporting the tubular paper filter element and permits the removal and replacement of such filter elements.
U.S. Pat. No. 4,304,580 to Gehl et al. discloses an air cleaner which includes a support having a first concave conical surface and compression means extending along the axis of the surface away from the apex of the surface. A hollow inner filter including a first end cap with a rim define a first convex conical surface having the same apex angle as the first concave surface, and a second end cap for axial engagement by the compression means. A hollow outer filter includes an end cap with a resilient lip extending inwardly to be sealingly received between the conical surfaces when the compression means engages the second end cap. The second end cap of the inner filter may have a second convex conical surface. The outer filter may have a second end cap with a resilient lip extending to be sealingly engaged by the second convex conical shape.
U.S. Pat. No. 4,350,592 to Kronsbein sets forth a cartridge filter for gases and liquids having a filter element clamped between an upper and lower cover. The filter includes a profile ring composed of a sealing compound which is firmly connected to the upper end face and an identical and corresponding profile ring firmly connected to the lower end face of the filter element. Sealing rings are embedded in the profile rings. The covers each includes one circumferential groove engaging around the sealing rings in a claw-like manner.
U.S. Pat. No. 4,728,421 to Moddemeyer teaches a resilient compressor ball compressed to urge an axially-movable circular knife-edge onto one end of a cylindrical filter element to form a seal therewith and to urge the filter element onto a fixed circular knife-edge having a fluid outlet opening therewithin to form a seal therewith. The movable knife-edge is concentrically formed on an axially-slidable tubular compressor element which confines the compressor ball within a hollow nut portion of a cap which is screwed onto a cylindrical shell having a base from which the fixed knife-edge extends in axial alignment with the movable knife-edge. When the cap is screwed onto the shell, the compression of the ball urges the movable knife edge against one end of the filter and the other end of the filter against the fixed knife-edge so as to seal the ends of the filter element and thus the seals formed at the knife-edges, while accommodating variances in the overall length of the filter element from its nominal length.
U.S. Pat. No. 4,764,275 Robichaud relates to a fluid filter and a method for attaching same to a filter mount of an engine in sealing relation is provided. The fluid filter include a filter media; a housing for the filter media; complimentary interengageable locking devices formed to radially on the filter and filter mount for engaging the filter and the filter mount; and a seal positioned between the housing and the filter mount. The locking devices include either: a first set of circumferentially spaced flanges formed on the inner wall of the housing and a second set of circumferentially spaced flanges formed on the filter mount; or a plurality of bolts attached to the filter mount or a plate attached to the housing and a corresponding plurality of holes formed in the plate or filter mount, respectively. The sealing means includes an annular, O-ring positioned between the housing and the filter mount.
U.S. Pat. No. 5,015,316 to Ostreicher et al. discloses a filter element adapted to be sealingly clamped in a filter housing. The element comprises a porous hollow cylindrical integral self-supporting bonded fibrous structure. The structure has thermally melt bonded to at least one end thereof, a thermoplastic polymer closed cell foam sealing gasket. The gasket is adapted to provide a sealing surface between the end of the cartridge and the sealing edge of the filter housing. In a preferred embodiment, the sealing edges of the filter housing used in conjunction with the aforedescribed filter element comprises at least two circular sealing edges concentric to the axis of the cylinder filter element. Such a combination provides a means for determining whether there is leakage past the sealing edges by the discoloration of the sealing gasket area between the concentric sealing edge by the liquid being filtered.
U.S. Pat. No. 5,211,846 to Kott et al. sets forth a replacement filter cartridge assembly including a filter cartridge element and a reusable supporting core assembly. The filter cartridge element is cylindrical in shape and has top and bottom end caps. Either the top end cap or the bottom end cap has an opening formed through its thickness which communicates with a central bore extending longitudinally through the filter cartridge element. The supporting core assembly includes a perforated tubular core and a sealing end cap mounted on one end of the core. The core is inserted through the top or bottom end cap opening and into the central bore of the filter cartridge element. The sealing end cap rests against either the top or bottom end cap of the filter cartridge element, while the other end of the tubular core contacts the inner side of the opposite end cap of the cartridge element. The supporting core is removable from the filter cartridge element when the filter cartridge needs to be replaced or cleaned, and may be reused on a clean filter cartridge element.
U.S. Pat. No. 5,298,160 to Ayers et al. discloses a filtration system for use to separate contamination from a liquid, including an elongated tubular housing which has a closed end and an open end. Located within the housing is an elongated perforated tubular member which has openings. A separating baffle for prohibiting flow between the housing and the tubular member is located near the closed end of housing. A first fluid portion in the housing is located between the filter element and the open end. A second port is located in the housing between the filter element and the closed end. The filter element is installed and removed through the open end of the housing and is installed between the housing and the member. A cover is placed over the open end of the housing in order that fluid which is contained within the housing may be sealed therein. A reservoir is located at the open end of the housing in order that fluid escaping from the housing during removal of the filter element may be contained within the reservoir.
Although the aforementioned prior art patent have made contributions to the filtering art, none of aforementioned prior art patents have completely solved the problems and needs of the filtering art.
Therefore, it is an object of this invention to provide an improved seal for sealing a filter element to a filter mounting incorporating a bonding pad to provide a seal between the filter element and the filter mounting.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting incorporating a bonding pad formed from a sintered matrix of metallic fibers to provide a seal between the filter element and the filter mounting.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting incorporating a mechanical fastener coacting between the filter element and the filter mounting for compressing said bonding pad to provide a seal between the filter element and the filter mounting.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting incorporating a bonding pad formed from the same material type as the filter element and the filter support.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which eliminates the need for a welding process.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which enables a first and a second end of a cylindrical filter media to be sealed to a first and a second end cap without a heating process.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which enables a first and a second end of a cylindrical filter media to be removably sealed to a first and a second end cap.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which enables a first and a second end of a cylindrical filter media to be sealed to a first and a second end cap without a heating process.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which incorporates a limited heating process for creating a frangible seal.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which incorporates a limited heating process for creating a tamper evident seal.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which is capable of withstanding a cleaning solvent and an elevated temperature.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting having superior sealing characteristics.
Another object of this invention is to provide an improved seal for sealing a filter element to a filter mounting which is reliable for use over an extended period of time.
The foregoing has outlined some of the more pertinent objects of the present invention.
These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.
The present invention is defined by the appended claims with specific embodiments being shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved seal for sealing a filter element to a filter mounting. The improved seal comprises a bonding pad formed from a sintered matrix of randomly oriented metallic fiber. The bonding pad is interposed between the filter element and the filter mounting. A mechanical fastener coacts between the filter element and the filter mounting for compressing the bonding pad to provide a seal between the filter element and the filter mounting.
In one example of the invention, the filter element comprises a filter media formed from a compressed web of a sintered matrix of randomly oriented metallic fibers. The metallic fibers of the filter media may be formed through a wire drawing process to provide a uniform diameter for uniformly filtering the fluid. Preferably, each of the metallic fibers having a diameter of less than 100 microns.
In another example of the invention, the filter element comprises a substantially cylindrical core having a first and a second core end with a plurality of apertures defined within the core. The filter media comprises a generally cylindrical filter media with the cylindrical core being disposed within and coaxial with the filter media for enabling the cylindrical core to support the cylindrical filter media thereby for enabling a fluid to flow through the filter media and to flow through the plurality of apertures defined within the core member. Preferably, the filter mounting is a metallic filter mounting and being of the same type of material as the metallic fibers of the bonding.
In a specific embodiment of the invention, the bonding pad comprises a resilient pad formed from a web of a sintered matrix of randomly oriented metallic fibers. Each of the metallic fibers of the bonding pad may be formed through a wire drawing process to provide a uniform diameter thereto. Preferably, each of the metallic fibers of the bonding pad has a diameter less than 100 microns.
The mechanical fastener may comprise a first mechanical fastener disposed relative to the filter element and a second mechanical fastener disposed relative to the filter mounting for compressing the bonding pad upon the engagement of the first mechanical fastener to the second mechanical fastener. In a specific example of the invention, the mechanical fastener comprises a first threaded fastener disposed relative to the filter element and a second threaded fastener disposed relative to the filter mounting for compressing the bonding pad upon the threaded engagement of the first threaded fastener to the second threaded fastener.
The improved seal of the present invention may include the bonding pad being optionally sinter bonded to the filter element and the filter mounting for creating a frangible seal between the filter element and the filter mounting.
The invention is also incorporated into the method of sealing a filter element to a filter mounting, comprising the steps of forming a bonding pad by sintering a matrix of randomly oriented fibers and interposing the bonding pad between the filter element and the filter mounting. A force is applied between the filter element and the filter mounting to compress the bonding pad to form a seal between the filter element and the filter mounting.
The step of applying a force may include applying a compressive force between the filter element and the filter mounting to compress the bonding pad to form a seal between the filter element and the filter mounting. In the alternative, the step of applying a force may include applying a compressive force created by a torque between the filter element and the filter mounting to compress the bonding pad to form a seal between the filter element and the filter mounting. Heat may be applied to sinter bond the bonding pad to the filter element and to the filter mounting. Preferably heat is applied for a period of time sufficient to provide a frangible sinter bond to secure the filter element and to the filter mounting and for enabling the frangible sinter bond to be severed to remove the filter element from the filter mounting.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.